The dissemnation of plasmid DNA elements among bacteria provides one of the most important mechanisms through which bacteria gain new pathogenic traits and other genetic characteristics that complicate clinical therapy. Using the F plasmid conjugation system of Escherichia coli as a model, we are studying the genes and gene products required for the transmission of F DNA from one cell to another. During our genetic and protein product analysis of genes in the F transfer region we have discovered a number of previously unrecognized coding sequences, and identified activities that are involved in making F-pilin. We now plan to complete a DNA sequence analysis of the F DNA segment which includes transfer genes traC through trbB and to characterize the transfer related function of the new loci in this region. We also propose experiments designed to characterize the biochemical steps of F-pilin synthesis and the role of traQ and other tra functions in this process.